1. Field of the Invention
The present invention relates to a low-noise block down-converter (LNB) which is applied to a satellite broadcast receiving system, and more particularly to an intelligent LNB which is implemented to, only when an LNB identification (ID) contained therein is the same as an ID of a satellite receiver connected therewith, provide a down-converted signal (intermediate frequency (IF) signal) to the satellite receiver, thereby making it possible to more securely prevent an ID card of the satellite receiver and/or a pay broadcast program from being duplicated.
2. Description of the Related Art
In general, an LNB is adapted to down-convert the frequency (about 10 GHz) of a satellite signal from a satellite antenna to a frequency (about 1 to 2 GHz) processable by a satellite receiver connected therewith. The satellite receiver functions to select a desired channel contained in an output signal from the LNB so that a user can view the selected channel.
FIG. 1 is a schematic view of a conventional LNB.
As shown in FIG. 1, the conventional LNB comprises a low-noise amplifier 11 for low-noise amplifying a satellite signal from a satellite antenna, a frequency converter 12 for down-converting the frequency (e.g., 10 GHz) of the satellite signal low-noise amplified by the low-noise amplifier 11 to a frequency (e.g., 950 MHz to 2150 MHz) processable by a satellite receiver and outputting the resulting IF signal, and an IF amplifier 13 for amplifying the IF signal from the frequency converter 12 to a level processable by the satellite receiver.
Meanwhile, a satellite broadcast includes a pay channel that a user can view only once a subscription fee has been paid. In order to view such a pay channel, the user has to pay a satellite broadcast provider a subscription fee for the pay channel in advance. Upon receipt of the subscription fee, the satellite broadcast provider allocates the user a specific code that enables the user to view the pay channel. Then, the user can view the pay channel through the satellite receiver using the specific code.
The specific code can be allocated in two methods, a keying method and an ID card method. The keying method is to key and store the specific code in the satellite receiver in advance. In this method, the satellite receiver reads the specific code stored therein so that the user can view the pay channel.
The ID card method is to insert, into the satellite receiver, an ID card having the specific code stored therein. In this method, the satellite receiver reads the specific code stored in the ID card inserted therein so that the user can view the pay channel.
The ID card method, of the above two methods, is more widely used than the keying method in that it provides greater convenience of use.
However, the ID card may be duplicated. In this case, the user may view the pay channel through the satellite receiver using the duplicated ID card, resulting in a duplication of a costly pay broadcast program without permission.
For this reason, in consideration of the fact that the ID card may be duplicated without permission, special security measures must be taken for the pay channel.